The thing about neck is that I injured my neck pretty bad dong neck work. And since then I've read just how easy it is to permantly screw up your neck with direct work...and fact that I had to learn the hard way. And my neck is PEMRMANTLY screwed. I can't even turn it without having to listen to it grind
And the thing is I was being careful. Using light weights, etc...
So I'm pretty paranoid about it and if you read up you'll see there are reasons to be and not just based on my own experience.
I'd advize doing a LOT less than you think is necessary. And I would try to do it more with you neck static or doing isometrics. So like if you were to use a neck harness don't 'curl' it up and down with your neck but support is with your neck. I don't really know how those things were meant to be used but that's how I'd do it. And read up as much as you can on HOW to do all that. Because once you mess it up it will affect all you lifting. And of course it can be very dangerous to injure you cervical spine.
The exercises I have found that I can do safely and that work very well is to do neck bridges. This is basically where you support your weight with your neck. Of course you don't have to start out on the floor. You can start out using a wall (wiht padding) so that you are only supporting a fraction of your weight. It actually is pretty easy, from what I've seen, to get your neck to hypertrophy.
But like the other said....just training traps and heavy deadlfits and pulling will make your neck bigger as well.